1. Field of the Invention
The present invention relates to a hard disk drive, a method for parking a magnetic head of the hard disk drive, and a computer readable recording medium recording a program to execute the method, and more particularly, to a hard disk drive which can park a magnetic head of the hard disk drive in a predetermined parking area without using a counter electromotive force of a spindle motor when the magnetic head is difficult to park using the counter electromotive force because the counter electromotive force of the spindle motor is very small as in a 1 inch or less compact hard disk drive used for mobile devices, a method for parking a magnetic head of the hard disk drive, and a computer readable recording medium recording a program to execute the method.
2. Description of Related Art
Hard disk drives (HDDs) formed of electronic parts and mechanical parts is are memory devices to record and reproduce data by converting digital electric pulses to a magnetic field that is more permanent. The HDDs are widely used as auxiliary memory devices of computer systems because of fast access time to a large amount of data.
With the recent increase in TPI (track per inch; a density in a direction along the rotation of a disk) and BPI (bits per inch; a density in a direction along the thickness of a disk), the HDD has achieved a high capacity and its application field has expanded. Accordingly, there has been a request for development of compact HDDs which can be used for portable electronic products such as notebooks, personal digital assistants (PDAs), and mobile phones. Actually, a compact HDD having a diameter of 0.85 inches, which has a size similar to a coin, has been recently developed and is expected to be used for mobile phones in the future.
The HDD includes a disk for recording data, a spindle motor for rotating the disk, and an actuator having a magnetic head to record data on the disk and reproduce data from the disk. The actuator pivots around a pivot shaft by means of a voice coil motor (VCM) and includes an actuator arm rotatably coupled to the pivot shaft, a slider on which a magnetic head is mounted, and a suspension installed at the actuator arm to support the slider to be elastically biased toward the surface of the disk.
One or more disks are installed with a predetermined interval therebetween to be rotated by the spindle motor. In general, a parking zone where the slider with the magnetic head is accommodated during parking off is provided at the inner circumferential side of the disk while a data zone where a magnetic signal is recorded is provided at the outer side of the parking zone.
During the recording and reproduction of data, a lift force generated by airflow moved by the rotation of the disk and an elastic force by the suspension act on the slider with the magnetic head. Accordingly, the slider maintains a state of being lifted above the data zone of the disk at a height where the lift force and the elastic force are balanced. Thus, the magnetic head mounted on the slider records and reproduces data with respect to the disk while maintaining a particular gap with the disk that is rotating. When the power is off and the rotation of disk is stopped, the lift force that lifts the slider disappears. Thus, the slider needs to be out of the data zone of the disk before the lift force disappears to prevent damage to the data zone due to a contact between the slider and the data zone. That is, before the rotation of disk is completely stopped, the actuator arm is rotated to move the slider to the parking zone of the disk. Accordingly, even when the rotation of disk is stopped, since the magnetic head is accommodated in the parking zone, the damage to the data zone can be prevented.
Therefore, when the power to the hard disk drive is cut off so that the rotation of disk is stopped, it is common that the magnetic head mounted on the slider is parked by moving the same to the parking zone of the disk before the rotation of disk is completed stopped.
In the meantime, as a method for parking the magnetic head in a safe place before the rotation of disk is stopped as the power is off, current is applied to a voice coil of the voice coil motor by a counter electromotive force of the spindle motor when the power is off so that the magnetic head is parked in a predetermined parking zone. For hard disk drives having a size such as 3.5 or 2.5 inches, since the counter electromotive force of the spindle motor is not small, the current needed to park the magnet head can be supplied. However, for compact hard disk drives having a size of 1 inch or less which is used for mobile devices, since the counter electromotive force is very small, it is difficult to park the magnetic head with the counter electromotive force only.
Considering the above problem, in a compact hard disk drive having a size of 1 inch or less, since it is difficult to apply current needed to park the magnetic head to the voice coil of the voice coil motor as the counter electromotive force of the spindle motor is very small, a capacitor electrically connected to the voice coil of the voice coil motor is installed on a printed circuit board (PCB). Thus, when the power is applied to the hard disk drive, current is charged to the capacitor and when the power is off, the current charged in the capacitor is discharged to the voice coil of the voice coil motor so that the magnetic head is parked.
However, when the magnetic head is parked by supplying the current charged in the capacitor that is electrically connected to the voice coil of the voice coil motor to the voice coil, the captor needs to be installed on the PCB. For the compact hard disk drive having a size of 1 inch or less that is used for mobile devices, since there is a limit in the area of the PCB, it is difficult to install a large number of capacitors. Even when a sufficient area for a large number of capacitor exists, since a lot of cost is needed to install the capacitors, a production cost is raised.